| Editorial | | BIB | Full-Text | 1-2 | |
| James Ritchie; Judy Vance; Satyandra Gupta | |||
| A dual-representation strategy for the virtual assembly of thin deformable objects | | BIBAK | Full-Text | 3-14 | |
| Vikalp Mishra; Krishnan Suresh | |||
| The two main objectives of virtual assembly are: (1) to train
assembly-operators through virtual assembly models, and (2) to simultaneously
evaluate products for ease-of-assembly. The focus of this paper is on
developing computational techniques for virtual assembly of thin deformable
beam and plate-like objects. To meet the objectives of virtual assembly, the
underlying computational technique must: (1) be carried out at a high
frame-rate (>20 frames/second), (2) be accurate (<5% error in deformation
and force estimation), (3) be conducive to collision detection, and (4) support
rapid design evaluations. We argue in this paper that popular computational
techniques such as 3-D finite element analysis, boundary element analysis and
classic beam/plate/shell analysis fail to meet these requirements. We therefore
propose a new class of dual representation techniques for virtual assembly of
thin solids, where the geometry is retained in its full 3-D form, while the
underlying physics is dimensionally reduced, delivering: (1) high computational
efficiency and accuracy (over 20 frames per second with <1% deformation
error), and (2) direct CAD model processing, i.e., the CAD model is not
geometrically simplified, and 3-D finite element mesh is not generated. In
particular, a small-size stiffness matrix with about 300 degrees of freedom per
deformable object is generated directly from a coarse surface triangulation,
and its LU-decomposition is then exploited during real-time simulation. The
accuracy and efficiency of the proposed method is established through numerical
experiments and a case study. Keywords: Virtual assembly; Deformation; Thin; Plates; Kirchhoff-Love;
Dual-representation | |||
| Coupling of interactive manufacturing operations simulation and immersive virtual reality | | BIBAK | Full-Text | 15-23 | |
| Denis V. Dorozhkin; Judy M. Vance; Gordon D. Rehn; Marco Lemessi | |||
| This paper presents a novel general-purpose simulation analysis application
that combines concurrent operations simulation with the advanced data
interrogation and user interaction capabilities of immersive virtual reality
systems. The application allows for interactive modification of the simulation
parameters, while providing the users with the available simulation information
by effectively placing the operator in the midst of the environment being
simulated. The major contribution of this research is the total integration of
the immersive virtual reality environment with the simulation, allowing users
in the environment to interactively change the inputs to the simulation as it
is running. Implementation and functionality details of the developed
application are presented. The experience of using the application to analyze a
manufacturing operation in a collaborative scenario is also discussed. Keywords: Concurrent operations simulation; Virtual reality | |||
| An integrated head pose and eye gaze tracking approach to non-intrusive visual attention measurement for wide FOV simulators | | BIBAK | Full-Text | 25-32 | |
| Hua Cai; Yingzi Lin | |||
| Eye gaze tracking is very useful for quantitatively measuring visual
attention in virtual environments. However, most eye trackers have a limited
tracking range, e.g., ±35° in the horizontal direction. This paper
proposed a method to combine head pose tracking and eye gaze tracking together
to achieve a large range of tracking in virtual driving simulation
environments. Multiple parallel multilayer perceptrons were used to reconstruct
the relationship between head images and head poses. Head images were
represented with the coefficients extracted from Principal Component Analysis.
Eye gaze tracking provides precise results on the front view, while head pose
tracking is more suitable for tracking areas of interest than for tracking
points of interest on the side view. Keywords: Eye gaze tracking; Head pose tracking; Multilayer perceptron (MLP); Visual
attention | |||
| Prototyping flexible touch screen devices using collocated haptic-graphic elastic-object deformation on the GPU | | BIBAK | Full-Text | 33-43 | |
| Arun Rakesh Yoganandan; P. Pat Banerjee; Cristian J. Luciano | |||
| Rapid advances in flexible display technologies and the benefits that they
provide are promising enough to consider them for futuristic mobile devices.
Current prototyping methods lack facilities to simulate such flexible touch
screen displays and the interaction with them. In this paper, we present a
technique that provides product developers a tool to interactively simulate
products featuring flexible displays, using Augmented Reality and Haptics. This
GPU-based algorithm is computationally inexpensive and efficient to deform a
polygonal mesh in real time while maintaining an acceptable haptic feedback.
The implementation of the algorithm has been found to be successful when
applied to a variety of product simulations. This simulation tool can enhance
or even replace traditional prototyping and facilitate testing of the prototype
at various stages of the design cycle. Keywords: Virtual reality prototyping; Flexible displays; Product simulation; Haptics | |||
| Real-time simulation for a virtual reality-based MIG welding training system | | BIBAK | Full-Text | 45-55 | |
| Terrence L. Chambers; Amit Aglawe; Dirk Reiners; Steven White | |||
| This paper describes a real-time welding simulation method for use in a
desktop virtual reality simulated Metal Inert Gas welding training system. The
simulation defines the shape of the weld bead, the depth of penetration, and
the temperature distribution in the workpiece, based on inputs from the
motion-tracking system that tracks the position of the welding gun as a
function of time. A finite difference method is used to calculate the
temperature distribution, including the width of the weld bead and the depth of
penetration. The shape of the weld bead is then calculated at each time step by
assuming a semi-spherical volume, based on the width of the weld bead, the
welding speed, and the wire feed rate. The real-time performance of the system
is examined, and results from the real-time simulation are compared to physical
tests and are found to have very good correlation for welding speeds up to
1,000 mm/min. Keywords: Virtual reality; Welding; Finite difference; Simulation; Training | |||
| VRMDS: an intuitive virtual environment for supporting the conceptual design of mechanisms | | BIBAK | Full-Text | 57-68 | |
| Juan Camilo Alvarez; Hai-Jun Su | |||
| This paper presents Virtual Reality Mechanism Design Studio (VRMDS), an
intuitive virtual environment for supporting the interactive design and
simulation of mechanisms. The studio allows users to build spatial or planar
mechanisms through intuitive operations and subsequently simulate their dynamic
motion. Written in Python script language, VRMDS provides 3D stereoscopic
immersive visualization, haptic enabled interaction, head and hand tracking and
a user-friendly graphical user interface. A data model for organizing the data
structure of links and commonly used mechanical joints is designed and
implemented upon the basis of the Vizard Virtual Reality (VR) library. Within
the virtual environment, the user can create links and assemble them into a
mechanism by defining joints between links. Simultaneously, a corresponding
MATLAB's SimMechanics model is automatically created at run time. The dynamics
simulation of mechanisms is enabled by interfacing with the dynamics solver
built-in SimMechanics. The user may choose to run the system in an immersive VR
environment or a desktop environment. The result is a versatile mechanism
design tool that is beneficial to the early stages of the design process. A
case study of a spatial mechanism is provided to demonstrate the usefulness of
this system in mechanism design. Keywords: Virtual reality; Conceptual design; Computer-aided design; Mechanism design;
Multi-body dynamics simulation; Haptic interfaces; SimMechanics | |||
| Automated generation of engineering rationale, knowledge and intent representations during the product life cycle | | BIBAK | Full-Text | 69-85 | |
| Raymond C. W. Sung; James M. Ritchie; Theodore Lim; Zoe Kosmadoudi | |||
| One of the biggest challenges in engineering design and manufacturing
environments is the effective capture of and decoding of tacit knowledge.
Fundamental to Life Cycle Engineering is the capture of engineering information
and knowledge created at all stages of the product development process, from
conceptual design through to product support and disposal. Consider this -- the
amount of vital information and knowledge lost when key design personnel retire
-- hence the need to capture meta-cognitive task-related strategies,
particularly to support knowledge reuse and training. Many methods have been
tried and tested with the successful few found to be very time consuming and
expensive to implement and carry out; consequently, there is a need to
investigate alternative paradigms for knowledge and information capture. This
paper reports on a current industrial case study on knowledge capture methods
employed by industrial partners in the design and manufacture of a variety of
electro-mechanical products. The results suggest the need for new kinds and
forms of knowledge capture methods and representation, particularly those
associated with individual design engineering tasks. Following the findings,
the paper presents a knowledge capture methodology for automatic real-time
logging, capture and post-processing of design data from a virtual reality
design system. Task-based design experiments were carried out with industrial
partners to demonstrate the effective, unobtrusive and automatic capture and
representation of various forms of design knowledge and information.
Qualitative and quantitative evaluation of knowledge representations were also
performed to determine which method was most effective at conveying design
knowledge and information for other engineers. Keywords: Knowledge capture; Cable harness design; Knowledge representation; User
logging; Design rationale; Design task analysis | |||
| Grasp programming by demonstration in virtual reality with automatic environment reconstruction | | BIBAK | Full-Text | 87-104 | |
| Jacopo Aleotti; Stefano Caselli | |||
| A virtual reality system enabling high-level programming of robot grasps is
described. The system is designed to support programming by demonstration
(PbD), an approach aimed at simplifying robot programming and empowering even
unexperienced users with the ability to easily transfer knowledge to a robotic
system. Programming robot grasps from human demonstrations requires an analysis
phase, comprising learning and classification of human grasps, as well as a
synthesis phase, where an appropriate human-demonstrated grasp is imitated and
adapted to a specific robotic device and object to be grasped. The virtual
reality system described in this paper supports both phases, thereby enabling
end-to-end imitation-based programming of robot grasps. Moreover, as in the PbD
approach robot environment interactions are no longer explicitly programmed,
the system includes a method for automatic environment reconstruction that
relieves the designer from manually editing the pose of the objects in the
scene and enables intelligent manipulation. A workspace modeling technique
based on monocular vision and computation of edge-face graphs is proposed. The
modeling algorithm works in real time and supports registration of multiple
views. Object recognition and workspace reconstruction features, along with
grasp analysis and synthesis, have been tested in simulated tasks involving 3D
user interaction and programming of assembly operations. Experiments reported
in the paper assess the capabilities of the three main components of the
system: the grasp recognizer, the vision-based environment modeling system, and
the grasp synthesizer. Keywords: Virtual reality; Environment modeling; Grasp programming; Glove interaction | |||
| The Virtual Trillium Trail and the empirical effects of Freedom and Fidelity on discovery-based learning | | BIBAK | Full-Text | 105-120 | |
| Maria C. R. Harrington | |||
| The Virtual Trillium Trail is a new kind of desktop virtual reality
application that crosses over into the area of geospatial, educational
simulations. Visual fidelity significantly impacts intrinsic learning, activity
in situ, and knowledge gained, independent of other factors. The main empirical
contribution of this report is on the impact of the user interface design
parameters of graphical fidelity and navigational freedom on learning outcomes.
A planned orthogonal contrast, Two-way ANOVA with the factors of Visual
Fidelity and Navigational Freedom -- both scaled, and set to high and low
levels -- shows significant impacts on the variables of Salient Events, a proxy
for discovery-based learning, and Knowledge Gained, as measured between a
pre-test and a post-test. Thus, there is strong empirical evidence to support
the use of desktop virtual environments, built with high-fidelity,
photo-realistic, and free navigational game engine technology, as educational
simulations for informal education. The high-level Visual Fidelity combined
with the high-level Navigational Freedom condition showed a mean learning gain
of 37.44% and is significantly superior to the low-level Visual Fidelity,
low-level Navigational Freedom condition, ceteris paribus. Keywords: Virtual reality; Serious games; Educational simulations;
Child-computer-environment interface; Discovery-based learning; Ecology
education; User interfaces; Three-dimensional graphics and realism | |||
| The Palenque project: evaluating interaction in an online virtual archaeology site | | BIBAK | Full-Text | 121-139 | |
| Erik Champion; Ian Bishop; Bharat Dave | |||
| This case study evaluated the effect on cultural understanding of three
different interaction modes, each teamed with a specific slice of the digitally
reconstructed environment. The three interaction modes were derived from an
initial descriptive theory of cultural learning as instruction, observation and
action. A major aim was to ascertain whether task performance was similar to
the development of understanding of the cultural context reached by
participation in the virtual environment. A hypothesis was that if task
performance is equivalent to understanding and engagement, we might be able to
evaluate the success of virtual heritage environments (through engagement and
education), without having to annoy the user with post-experience
questionnaires. However, results suggest interaction in virtual heritage
environments is so contextually embedded; subjective post-test questionnaires
can still be more reliable than evaluating task performance. Keywords: Palenque; Virtual heritage; Cultural learning; Mayan | |||
| Discriminability-based evaluation of transmission capability of tactile transmission systems | | BIBAK | Full-Text | 141-150 | |
| Shogo Okamoto; Masashi Konyo; Satoshi Tadokoro | |||
| Tactile transmission systems deliver tactile information such as texture
roughness to operators of robotic systems. Such systems are typically composed
of tactile sensors that sense the physical characteristics of textures and
tactile displays that present tactile stimuli to operators. One problem
associated with tactile transmission systems is that when the system has a
bottleneck, it is difficult to identify whether the tactile sensor, tactile
display, or perceptual ability of the user is the cause because they have
different performance criteria. To solve this problem, this study established
an evaluation method that uses the discriminability index as an evaluation
criterion. The method lets tactile sensors, displays, and human tactile
perception be assessed in terms of the ability to transmit physical quantities;
the same criterion is used for all three possible causes so that their
abilities can be directly compared. The developed method was applied to a
tactile-roughness transmission system (Okamoto et al. 2009), and its tactile
sensor was identified as the bottleneck of the system. Keywords: Assessment of man-machine system; Discriminability index; Performance
measurement; Tactile display; Tactile sensor | |||
| RTIL-system: a Real-Time Interactive L-system for 3D interactions with virtual plants | | BIBAK | Full-Text | 151-160 | |
| Ludovic Hamon; Emmanuelle Richard; Paul Richard; Rachid Boumaza | |||
| The L-system is a rewriting process based on formal grammar and is used to
generate 3D, dynamic structures such as virtual plants and fractal graphics. In
previous works, we highlighted that existing L-system software applications and
programs are limited, either in terms of human interaction or in terms of
modelling. In particular, few of them allow the user to interact with virtual
plants during their growth. Our own L-system engine was developed and called
the real-time interactive L-system (RTIL-system). The RTIL-system covers most
important L-system extensions such as parametric and context-sensitive
features. Furthermore, real-time interactions with the user and the environment
with respect to L-system formalism are available. This paper presents an
RTIL-system focusing on human interaction, the Partial Interactive Derivation
(PID) concept and further progress by the extension of PID to context-sensitive
rules. To illustrate the potential of the RTIL-system, the effect of various
interactive tasks such as sub-axis additions, pruning and bending on the
subsequent dynamic development of virtual plants is described. Keywords: Virtual reality; L-system; Real-time interaction; Virtual plant; Fractal | |||
| A novel approach in rehabilitation of hand-eye coordination and finger dexterity | | BIBAK | Full-Text | 161-171 | |
| Y. Shen; P. W. Gu; S. K. Ong; A. Y. C. Nee | |||
| Stroke patients or victims who have been involved in serious accidents often
suffer from impaired hand-eye coordination and muscle dexterity. Products, such
as nine-hole pegboards, have been designed to help rehabilitate various skills,
e.g., perceptual accuracy and finger dexterity. Patients who do not have
sufficient muscle strength would not be able to carry out such traditional
exercises. This paper presents the research aims at providing a fresh and
viable approach to physiotherapy for such patients while emulating the
rehabilitation capabilities of traditional products. In this paper, a novel
approach, AR-Rehab, for the rehabilitation of hand-eye coordination and finger
dexterity has been developed incorporating Augmented Reality (AR) technology.
In this application, the users can interact with virtual piano keys in a
real-life scene by moving the real hands wearing data-gloves to detect the
flexing of the fingers and markers to detect the position of the hands. Keywords: Augmented reality; Rehabilitation; Hand-eye coordination; Finger dexterity | |||
| Haptic interpersonal communication: improvement of actions coordination in collaborative virtual environments | | BIBAK | Full-Text | 173-186 | |
| Jean Simard; Mehdi Ammi | |||
| This article explores the use of haptic feedback for interpersonal
communication in collaborative virtual environments. After a detailed
presentation of all communication mechanisms involved, we propose the
investigation of a low-level communication approach through the feedthrough
mechanism. This channel is used to communicate kinematic information about a
partner's gestures during closely coupled collaboration. Several communication
metaphors, with complementary behaviors, were investigated to improve the
coordination between two partners during an assembly task. The results clearly
show the role of communication strategies for the improvement of gesture
coordination and highlight the correlation between applied force and the level
of efficiency. Keywords: Collaborative virtual environments; Haptics; Awareness; Sensorial
communication; Communication metaphors | |||
| Performance improvement of Distributed Virtual Environments by exploiting objects' attributes | | BIBAK | Full-Text | 187-203 | |
| Christos Bouras; Eri Giannaka; Thrasyvoulos Tsiatsos | |||
| Distributed virtual environments need to address issues related to the
control of network traffic, resource management, and scalability. Given the
distributed nature of these environments, the main problems they need to
overcome are the efficient distribution of workload among the servers and the
minimization of the communication cost. In this direction, a lot of work has
been done and numerous relevant techniques and algorithms have been proposed.
The majority of these approaches mainly focus on user entities and their
interactions. However, most of actual DVE systems include additional and
non-dynamic elements, denoted as objects, whose presence can affect users'
behavior. This paper introduces virtual objects' attributes and proposes two
approaches that exploit these attributes in order to handle workload assignment
and communication cost in DVE systems. Both approaches take into account
scenario-specific aspects of DVE systems, such as the impact that entities'
attributes have on each other and the way this impact can affect the system's
state. These scenario-specific aspects are then combined with quantitative
factors of the system, such as workload, communication cost, and utilization.
The experiments conducted in order to validate the behavior of the proposed
approach show that the incorporation of object's presence can improve the DVE
system's performance. More specifically, objects' presence and their attributes
can assist in the significant reduction in the communication cost along with
effective workload distribution among the system's servers. Keywords: Distributed virtual environments; Load balancing; VR techniques and systems | |||
| A methodology for optimal voxel size computation in collision detection algorithms for virtual reality | | BIBAK | Full-Text | 205-213 | |
| G. Echegaray; D. Borro | |||
| Real-time Virtual Reality applications require accuracy but are also time
dependent; therefore, in these environments, the time consumption is
particularly important. For that reason, when facing the problem of Collision
Detection for a Virtual Reality application, we firstly focus our attention on
optimizing time performance for collisions among objects. Spatial Partitioning
algorithms have been broadly used in Collision Detection. In particular,
voxel-based methods are simple and quick, but finding the optimum voxel size is
not trivial. We propose a methodology to easily determine the optimal voxel
size for Collision Detection algorithms. Using an algorithm which represents
volumetric objects with tetrahedra as an example, a performance cost function
is defined in order to analytically bound the voxel size that gives the best
computation times. This is made by inferring and estimating all the parameters
involved. Thus, the cost function is delimited to depend only on geometric
data. By doing so, it is possible to determine the optimal voxelization for any
algorithm and scenario. Several solutions have been researched and compared.
Experimental results with theoretical and real 3D models have validated the
methodology. The reliability of our research has also been compared with
traditional experimental solutions given by previous works. Keywords: Collision detection; Voxel size; Uniform spatial partitioning; Optimization | |||
| An integrated virtual environment for feasibility studies and implementation of aerial MonoSLAM | | BIBAK | Full-Text | 215-232 | |
| M. A. Amiri Atashgah; S. M. B. Malaek | |||
| This work presents a complete framework of an integrated aerial virtual
environment (IAVE), which could effectively help implementing MonoSLAM
(single-camera simultaneous localization and mapping) on an aerial vehicle. The
developed system allows investigating different flight conditions without using
any preloaded maps or predefined features. A 3D graphical engine integrated
with a full 6 DOF aircraft dynamic simulator together with its trajectory
generator completes the package. The 3D engine generates and accumulates
real-time images of a general camera installed on the aerial vehicle. We
effectively exploit C++ to develop the 3D graphics engine (3DGE) and all its
associated visual effects, including different types of lighting, climate
conditions, and moving objects. The existing 3DGE exploits the so-called Frenet
Adapted Frames (FAF) with constrained angular velocities that is very effective
in motion modeling of both ground and aerial moving objects. An
in-house-developed MATLAB GUI puts into service the offline MonoSLAM system,
which is very user friendly. The current version of IAVE effectively employs
the so-called Inverse Depth Parameterization notions for features' depth
estimation in monocular SLAM, where different case studies show its dependable
results for low-cost aerial navigation of a general aviation low-speed
aircraft. Keywords: 3D graphics engine; Virtual environment; MonoSLAM; General aviation; Aerial
navigation | |||
| Virtual reality as a communication process | | BIBAK | Full-Text | 233-241 | |
| Daniele Marini; Raffaella Folgieri; Davide Gadia; Alessandro Rizzi | |||
| In this work, we consider immersive Virtual Reality (VR) as a communication
process between humans, mediated by computer systems, which uses interaction,
visualization, and other sensory stimuli to convey information. From this
viewpoint, it is relevant to understand how VR can solve a given communication
problem, what is therefore the expressive power of VR system, i.e., its ability
in establishing the communication, what are the guidelines to design an
effective system, and what are the more relevant models of VR applications.
Firstly, we try to clarify the notion of reality in Virtual Reality systems and
conclude that reality is not an intrinsic characteristic of VR, rather the
result of a conventional way of coding information. The purpose of coding is to
lead the observer to the conclusion that the VR set is what is called in
italian as verisimile (from Latin veri similis), i.e.,
"similar-to-the-real-thing". So the creation of an effective VR application is
an artifice or an illusion. But in order to avoid an over-reliance on the
creativity of the VR designer, we intend to identify a solid ground on which
different kinds of VR solutions can be considered in terms of their ability to
solve the desired communication objective. To this aim, we will rely on methods
derived from rhetoric to semiotics. Keywords: Virtual Reality; Semiotics; Communication; Realism | |||
| Immersive manipulation of virtual objects through glove-based hand gesture interaction | | BIBAK | Full-Text | 243-252 | |
| Gan Lu; Lik-Kwan Shark; Geoff Hall; Ulrike Zeshan | |||
| Immersive visualisation is increasingly being used for comprehensive and
rapid analysis of objects in 3D and object dynamic behaviour in 4D. Challenges
are therefore presented to provide natural user interaction to enable
effortless virtual object manipulation. Presented in this paper is the
development and evaluation of an immersive human-computer interaction system
based on stereoscopic viewing and natural hand gestures. For the development,
it is based on the integration of a back-projection stereoscopic system for
object and hand display, a hybrid inertial and ultrasonic tracking system to
provide the absolute positions and orientations of the user's head and hands,
as well as a pair of high degrees-of-freedom data gloves to provide the
relative positions and orientations of digit joints and tips on both hands. For
the evaluation, it is based on a two-object scene with a virtual cube and a CT
(computed tomography) volume created for demonstration of real-time immersive
object manipulation. The system is shown to provide a correct user view of
objects and hands in 3D with depth, as well as to enable a user to use a number
of simple hand gestures to perform basic object manipulation tasks involving
selection, release, translation, rotation and scaling. Also included in the
evaluation are some quantitative tests of the system performance in terms of
speed and latency. Keywords: Hand gesture tracking and recognition; Immersive stereoscopic visualisation;
Virtual object manipulation | |||
| NAVIG: augmented reality guidance system for the visually impaired | | BIBAK | Full-Text | 253-269 | |
| Brian F. G. Katz; Slim Kammoun; Gaëtan Parseihian; Olivier Gutierrez | |||
| Navigating complex routes and finding objects of interest are challenging
tasks for the visually impaired. The project NAVIG (Navigation Assisted by
artificial VIsion and GNSS) is directed toward increasing personal autonomy via
a virtual augmented reality system. The system integrates an adapted geographic
information system with different classes of objects useful for improving route
selection and guidance. The database also includes models of important
geolocated objects that may be detected by real-time embedded vision
algorithms. Object localization (relative to the user) may serve both global
positioning and sensorimotor actions such as heading, grasping, or piloting.
The user is guided to his desired destination through spatialized semantic
audio rendering, always maintained in the head-centered reference frame. This
paper presents the overall project design and architecture of the NAVIG system.
In addition, details of a new type of detection and localization device are
presented. This approach combines a bio-inspired vision system that can
recognize and locate objects very quickly and a 3D sound rendering system that
is able to perceptually position a sound at the location of the recognized
object. This system was developed in relation to guidance directives developed
through participative design with potential users and educators for the
visually impaired. Keywords: Assisted navigation; Guidance; Spatial audio; Visually impaired assistive
device; Need analysis | |||
| Toward the design of transitional interfaces: an exploratory study on a semi-immersive hybrid user interface | | BIBAK | Full-Text | 271-288 | |
| Felipe G. Carvalho; Daniela G. Trevisan; Alberto Raposo | |||
| A task that can be decomposed into subtasks with different technological
demands may be a challenge, since it requires multiple interactive environments
as well as transitions between them. Some of these transitions may involve
changes in hardware devices and interface paradigms at the same time. Some
previous works have proposed various setups for hybrid user interfaces, but
none of them focused on the design of transition interactions. Our work
emphasizes the importance of interaction continuity as a guideline in the
design and evaluation of transitional interfaces within a hybrid user interface
(HUI). Finally, an exploratory study demonstrates how this design aspect is
perceived by users during transitions in an HUI composed by three interactive
environments. Keywords: Transitional interfaces; Hybrid user interfaces; Continuity properties | |||
| Camera space shadow maps for large virtual environments | | BIBAK | Full-Text | 289-299 | |
| Ivica Kolic; Zeljka Mihajlovic | |||
| This paper presents a new single-pass shadow mapping technique that achieves
better quality than the approaches based on perspective warping, such as
perspective, light-space, and trapezoidal shadow maps. The proposed technique
is appropriate for real-time rendering of large virtual environments that
include dynamic objects. By performing operations in camera space, this
solution successfully handles the general and the dueling frustum cases and
produces high-quality shadows even for extremely large scenes. This paper also
presents a fast nonlinear projection technique for shadow map stretching that
enables complete utilization of the shadow map by eliminating wastage. The
application of stretching results in a significant reduction in unwanted
perspective aliasing, commonly found in all shadow mapping techniques.
Technique is compared with other shadow mapping techniques, and the benefits of
the proposed method are presented. The proposed shadow mapping technique is
simple and flexible enough to handle most of the special scenarios. An API for
a generic shadow mapping solution is presented. This API simplifies the
generation of fast and high-quality shadows. Keywords: Shadow maps; Real-time shadows; Dynamic shadows; Virtual environments | |||
| Supporting cognitive processing with spatial information presentations in virtual environments | | BIBAK | Full-Text | 301-314 | |
| Eric D. Ragan; Doug A. Bowman; Karl J. Huber | |||
| While it has been suggested that immersive virtual environments could
provide benefits for educational applications, few studies have formally
evaluated how the enhanced perceptual displays of such systems might improve
learning. Using simplified memorization and problem-solving tasks as
representative approximations of more advanced types of learning, we are
investigating the effects of providing supplemental spatial information on the
performance of learning-based activities within virtual environments. We
performed two experiments to investigate whether users can take advantage of a
spatial information presentation to improve performance on cognitive processing
activities. In both experiments, information was presented either directly in
front of the participant, at a single location, or wrapped around the
participant along the walls of a surround display. In our first experiment, we
measured memory scores and analyzed participant strategies for a memorization
and recall task. In addition to comparing spatial and non-spatial
presentations, we also varied field of view and background imagery. The results
showed that the spatial presentation caused significantly better memory scores.
Additionally, a significant interaction between background landmarks and
presentation style showed that participants used more visualization strategies
during the memorization task when background landmarks were shown with spatial
presentations. To investigate whether the advantages of spatial information
presentation extend beyond memorization to higher level cognitive activities,
our second experiment employed a puzzle-like task that required critical
thinking using the presented information. Focusing only on the effects of
spatial presentations, this experiment measured task performance and mental
workload. The results indicate that no performance improvements or mental
workload reductions were gained from the spatial presentation method compared
with a non-spatial layout for our problem-solving task. The results of these
two experiments suggest that supplemental spatial information can affect mental
strategies and support performance improvements for cognitive processing and
learning-based activities. However, the effectiveness of spatial presentations
is dependent on the nature of the task and a meaningful use of space and may
require practice with spatial strategies. Keywords: Virtual environments; Memory; Cognition; Learning; Space | |||
| Evaluation of an electronic video game for improvement of balance | | BIBAK | Full-Text | 315-323 | |
| Kristiina M. Valter McConville; Sumandeep Virk | |||
| Virtual environments have been investigated for fitness and medical
rehabilitation. In this study, the Sony EyeToy® and PlayStation 2® were
used with the AntiGrav™ game to evaluate their potential for improving
postural balance. The game required lateral head, body, and arm movements. The
performance on balance tests of subjects who trained for 3 weeks with this game
was compared to the performance of controls who were not trained. Training
subjects showed improvement for two of the three tests (each testing a
different facet of balance), suggesting specificity of training, while control
subjects did not show significant improvement on any test. Simulator sickness
questionnaire results showed a variety of mild symptoms, which decreased over
the training sessions. Motor learning analysis of the game scores showed that
mastery had been achieved on the easier level in the game, but not on the
second level of difficulty. This reflects the potential for continued learning
and training through advanced levels within a game. A model parameter using the
time constants of game score improvement was developed, which could be used to
quantify the difficulty for any video game design. The results suggest that
this video game could be used for some aspects of balance training. Keywords: Balance training; Difficulty model; Motor learning; Simulator sickness;
Video game; Virtual environment | |||
| Overcoming the information overload problem in a multiform feedback-based virtual reality system for hand motion rehabilitation: healthy subject case study | | BIBAK | Full-Text | 325-334 | |
| Sha Ma; Martin Varley; Lik-Kwan Shark; Jim Richards | |||
| The use of composite multiple feedback in a newly proposed virtual reality
system enables the patient to perceive similar real-world performance in the
virtual world. However, it might cause information overload, which makes the
patient feel confused and distracted during training. The aim of this study is
to investigate the effectiveness of having separate function-specific feedback
pre-training prior to the final multiform feedback task. During the evaluating
tests with thirty healthy subjects, it has been found that effective
pre-training set could overcome the problem in the main task. Minor
modifications on the pre-training set could overcome or aggravate the problem,
which indicates the importance of choosing the correct pre-training parameters. Keywords: Virtual world; User training for immersive environment; Multiform feedback;
Hand motion; Function rehabilitation; EMG | |||